Now the title above would be better on those dodgy sites but however theres such a thing as Legal Public Domain and Freeware roms and its those ill tell you about, the great site PD ROMS.com has thousands of roms for every system emulated here, so be sure to check them out here --> http://www.pdroms.de/index.php
Also our sister sites have PD rom zipfiles with many roms in each, Xbox Evolution has Nes, Snes, PC Engine and Atari 2600 roms here --> http://xbox-emulation.dcemu.co.uk/
Amongst the legal roms theres some genuine awesome games, try em and see